Technology has advanced to the stage where a variety of objects are constructed with sub-micron features. For example, computer processors are now designed with sub-micron dimensions. And, a new class of medical devices, known as “micro-medical” devices, also includes sub-micron components.
Quality control and other inspections must be completed on these miniature features. However, measurement systems capable of sub-micron inspection require their own complex technology. These devices generally include a high-powered microscope and extremely precise positioning equipment. Illumination systems, that include one or more lamps, provide the necessary light. However, variations in lamp intensity can cause measurement differences in otherwise identical parts. These illumination variations might occur when replacing lamps, when a lamp ages, or when measuring otherwise identical parts on different systems. What is true for lamps is also true for cameras and optics. One camera may not yield the same results as another on a given measurement system. Therefore, a need exists for a method and apparatus for calibrating a measurement system that will enable consistent measurements.